Power supply networks with intermediate circuits, in particular DC intermediate circuits, are known from their use in vehicles powered by electricity. The power supply networks are used, for example, to couple batteries and electrical machines, in particular engines. The DC voltage is here transferred, for example, from the battery in the power supply network to an inverter and converted into a multi-phase AC voltage to supply the electrical machine. Current and voltage peaks occur during the switching procedures required for this. In order to form an energy buffer and hence attenuate these current peaks and voltage peaks, an intermediate circuit capacitor is provided, for example, between the battery and the inverter. Once the vehicle has stopped operating, the battery is decoupled from the power supply network by means of switches. When the consumers connected to the power supply network are also switched off and no longer consume energy, the charging energy remains in the intermediate circuit capacitor. A voltage, in particular a high voltage, is thus present at the power supply network and hence at the conductive parts to which the intermediate circuit capacitor is connected. The power supply network, in particular the DC power supply network that is connected directly to the intermediate circuit capacitor, is termed an intermediate circuit. It is desirable that, once a vehicle has stopped operating, there is no longer any voltage at the power supply network of the vehicle or the voltage that is present is below at least one predeterminable voltage value, so that there is no longer any risk for passengers and maintenance operatives or the emergency services. To this end, a method is known from DE 10 2009 055 053 for discharging the intermediate circuit capacitor in a high-voltage network by means of a discharge circuit.